182 lines
6.9 KiB
JavaScript
182 lines
6.9 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = autoInject;
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var _auto = require('./auto.js');
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var _auto2 = _interopRequireDefault(_auto);
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var _wrapAsync = require('./internal/wrapAsync.js');
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var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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var FN_ARGS = /^(?:async\s)?(?:function)?\s*(?:\w+\s*)?\(([^)]+)\)(?:\s*{)/;
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var ARROW_FN_ARGS = /^(?:async\s)?\s*(?:\(\s*)?((?:[^)=\s]\s*)*)(?:\)\s*)?=>/;
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var FN_ARG_SPLIT = /,/;
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var FN_ARG = /(=.+)?(\s*)$/;
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function stripComments(string) {
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let stripped = '';
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let index = 0;
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let endBlockComment = string.indexOf('*/');
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while (index < string.length) {
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if (string[index] === '/' && string[index + 1] === '/') {
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// inline comment
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let endIndex = string.indexOf('\n', index);
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index = endIndex === -1 ? string.length : endIndex;
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} else if (endBlockComment !== -1 && string[index] === '/' && string[index + 1] === '*') {
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// block comment
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let endIndex = string.indexOf('*/', index);
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if (endIndex !== -1) {
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index = endIndex + 2;
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endBlockComment = string.indexOf('*/', index);
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} else {
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stripped += string[index];
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index++;
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}
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} else {
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stripped += string[index];
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index++;
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}
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}
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return stripped;
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}
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function parseParams(func) {
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const src = stripComments(func.toString());
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let match = src.match(FN_ARGS);
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if (!match) {
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match = src.match(ARROW_FN_ARGS);
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}
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if (!match) throw new Error('could not parse args in autoInject\nSource:\n' + src);
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let [, args] = match;
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return args.replace(/\s/g, '').split(FN_ARG_SPLIT).map(arg => arg.replace(FN_ARG, '').trim());
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}
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/**
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* A dependency-injected version of the [async.auto]{@link module:ControlFlow.auto} function. Dependent
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* tasks are specified as parameters to the function, after the usual callback
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* parameter, with the parameter names matching the names of the tasks it
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* depends on. This can provide even more readable task graphs which can be
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* easier to maintain.
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*
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* If a final callback is specified, the task results are similarly injected,
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* specified as named parameters after the initial error parameter.
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*
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* The autoInject function is purely syntactic sugar and its semantics are
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* otherwise equivalent to [async.auto]{@link module:ControlFlow.auto}.
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*
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* @name autoInject
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* @static
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* @memberOf module:ControlFlow
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* @method
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* @see [async.auto]{@link module:ControlFlow.auto}
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* @category Control Flow
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* @param {Object} tasks - An object, each of whose properties is an {@link AsyncFunction} of
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* the form 'func([dependencies...], callback). The object's key of a property
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* serves as the name of the task defined by that property, i.e. can be used
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* when specifying requirements for other tasks.
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* * The `callback` parameter is a `callback(err, result)` which must be called
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* when finished, passing an `error` (which can be `null`) and the result of
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* the function's execution. The remaining parameters name other tasks on
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* which the task is dependent, and the results from those tasks are the
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* arguments of those parameters.
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* @param {Function} [callback] - An optional callback which is called when all
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* the tasks have been completed. It receives the `err` argument if any `tasks`
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* pass an error to their callback, and a `results` object with any completed
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* task results, similar to `auto`.
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* @returns {Promise} a promise, if no callback is passed
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* @example
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*
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* // The example from `auto` can be rewritten as follows:
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* async.autoInject({
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* get_data: function(callback) {
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* // async code to get some data
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* callback(null, 'data', 'converted to array');
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* },
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* make_folder: function(callback) {
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* // async code to create a directory to store a file in
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* // this is run at the same time as getting the data
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* callback(null, 'folder');
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* },
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* write_file: function(get_data, make_folder, callback) {
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* // once there is some data and the directory exists,
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* // write the data to a file in the directory
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* callback(null, 'filename');
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* },
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* email_link: function(write_file, callback) {
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* // once the file is written let's email a link to it...
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* // write_file contains the filename returned by write_file.
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* callback(null, {'file':write_file, 'email':'user@example.com'});
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* }
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* }, function(err, results) {
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* console.log('err = ', err);
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* console.log('email_link = ', results.email_link);
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* });
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*
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* // If you are using a JS minifier that mangles parameter names, `autoInject`
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* // will not work with plain functions, since the parameter names will be
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* // collapsed to a single letter identifier. To work around this, you can
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* // explicitly specify the names of the parameters your task function needs
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* // in an array, similar to Angular.js dependency injection.
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*
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* // This still has an advantage over plain `auto`, since the results a task
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* // depends on are still spread into arguments.
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* async.autoInject({
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* //...
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* write_file: ['get_data', 'make_folder', function(get_data, make_folder, callback) {
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* callback(null, 'filename');
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* }],
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* email_link: ['write_file', function(write_file, callback) {
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* callback(null, {'file':write_file, 'email':'user@example.com'});
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* }]
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* //...
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* }, function(err, results) {
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* console.log('err = ', err);
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* console.log('email_link = ', results.email_link);
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* });
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*/
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function autoInject(tasks, callback) {
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var newTasks = {};
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Object.keys(tasks).forEach(key => {
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var taskFn = tasks[key];
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var params;
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var fnIsAsync = (0, _wrapAsync.isAsync)(taskFn);
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var hasNoDeps = !fnIsAsync && taskFn.length === 1 || fnIsAsync && taskFn.length === 0;
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if (Array.isArray(taskFn)) {
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params = [...taskFn];
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taskFn = params.pop();
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newTasks[key] = params.concat(params.length > 0 ? newTask : taskFn);
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} else if (hasNoDeps) {
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// no dependencies, use the function as-is
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newTasks[key] = taskFn;
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} else {
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params = parseParams(taskFn);
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if (taskFn.length === 0 && !fnIsAsync && params.length === 0) {
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throw new Error("autoInject task functions require explicit parameters.");
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}
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// remove callback param
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if (!fnIsAsync) params.pop();
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newTasks[key] = params.concat(newTask);
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}
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function newTask(results, taskCb) {
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var newArgs = params.map(name => results[name]);
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newArgs.push(taskCb);
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(0, _wrapAsync2.default)(taskFn)(...newArgs);
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}
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});
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return (0, _auto2.default)(newTasks, callback);
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}
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module.exports = exports.default; |